Rounding up fascinating news and research in the field of forensic science.

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Month: June 2015

What is your current job role and what does this position typically involve?

I’m a Forensic Identification Scientist at the Surete du Quebec provincial police in Canada. My job is to develop fingermarks on exhibits, either in the lab or directly at the crime scene if required. I typically use scientific methods involving chemistry, physics, biology and fluorescence to visualize latent fingermark. I also do research and development. I develop new methods and/or technologies to find fingermarks or I assess technologies newly available on the market to determine if it is worth the investment for our lab.

How did you end up working in your current field?

I’m a policeman’s son, so law enforcement work has always been part of my life. I used to say I was raised in a police station! At University, I chose to study sciences. When I learned that it was possible to work for the police community as a forensic scientist, I was immediately interested. I started in the forensic identification field as a lab technician immediately after my microbiology degree. I continued my studies in parallel with my work with a Masters in Technology assessment and management. Eventually, I got a Forensic Identification Scientist position. I’m still studying today, completing my PhD in Forensic Science at Lausanne University.

What are the major pros and cons of your job?

Pros: As a Forensic Identification Scientist, you are really involved in the investigation process. You can see the evidence of a crime even before the evening news talk about this so-called evidence. You will always be aware of the true story of a crime, not the official one for television. For someone who seeks the truth, that’s great! As a forensic identification scientist, you bring science to the law enforcement field, helping them in their investigation by providing new facts and evidence. Your work really has a big impact on justice. It is possible to find evidence to convict a criminal, but also to exonerate the innocent. We work in the lab, but we also have the chance, on specific crimes, to work directly at the crime scene. But the best part of the job remains, when working on an investigation that seems to give no result, and then suddenly you find THE fingermark that could change everything. Whether it gives a hit on AFIS or not, this fingermark gives hope to the team that the resolution of the investigation is still possible. The satisfaction felt is indescribable! You really get the feeling of being an important member of the investigation team!

Cons: Obviously, the forensic identification scientist knows the truth about a lot of files, but this work requires a high degree of confidentiality and you won’t be able to talk about it to anyone, even your loved ones. Gossip lovers beware! This scientific job also involves you being employed by the government… so money is always an object. This means that your salary is usually quite low, and in Canada, even lower than the police officer. So you work for passion of the field, not for money. You will also undergo frequent budget cuts and live with the motto to always do more with less. On the working environment side, expect to have to work with cadavers (fingermarks on skin, crime scenes), evidence covered with putrefaction fluid, guns, machetes stained with blood, and lots of other unsavory and unusual evidence. Fear of blood is not an option. Finally, you must be available. If a crime requires your immediate presence on the scene, be it day or night, or on the weekend, you need to go, even if you were in the middle of a dinner with friends.

How do you feel your field of work has changed over recent years?

The forensic identification field has evolved extremely rapidly in the recent years. Several universities began research programs in forensic identification, feeding the field with much scientific and technological innovation. I would say that the forensic identification field is in good health and has a very positive prospective for growth!

When thinking about your work history, are there any particular cases/investigations that stick in your mind?

I distinctly remember three stories related to the morgue, the lab and the crime scene.

Let’s start with the morgue. I remember one case where we were looking for a bloody fingermark on the skin of a poor victim who was raped and brutally murdered. We were using a reagent called Ortho-Tolidine to discover traces of blood invisible to the naked eye. The results were slow in coming, and we were not very enthusiastic. Suddenly, after spraying, a very faint green fingermark began to appear… I remember our excitement when we discovered this fingermark was suitable for research in the AFIS system. It was like winning the lotto! Unfortunately, this story ends badly. The fingermark found was not able to identify a suspect. You should know that to be identified, a fingermark donor must be part of the AFIS database. Probably, our potential suspect was never convicted or sentenced, so his fingerprints were not in the database.

Now the lab. I remember the four years work I had to invest in developing a new treatment for fingermark development. I was looking at the time for a new method that would be less expensive and easier to use; that would enable us to develop fingermarks on wet porous surfaces such as wet paper or cardboard. I finally succeeded in developing the Oil Red O. I remember the feeling of accomplishment I had! Everything was amplified by the hope that my contribution would benefit the Forensic Identification discipline and eventually allow me to be recognized in the field for my research. I always wanted to leave my (finger)mark on the forensic identification field! 😉

Finally, the crime scene. I remember being called to a crime scene for a murder case where we had to find fingermarks using fluorescence. It was the kind of murder where the investigation has no trail to follow and relies entirely on finding fingermarks. So we used multiple wavelengths on the scene to search for fingermarks having an inherent fluorescence. We found some: some only visible with UV, others only with the laser. We were very happy! As the surface of the exhibit seemed to respond very well, we decided to chemically treat the latter with cyanoacrylate and Rhodamine 6G to see if we could find some more… We found 4. What was great in this case, is that some prints were visible only with UV, others with laser, while the chemical was developing new ones, without developing the ones we already had found! A brilliant demonstration of the power of the sequential processing of evidence. The story also ends well for that matter, since the fingermarks identified a culprit.

Do you have any advice for those seeking a career in your field of work?

Going into this field is very difficult in Canada, since there is a pretty low number of positions for civilians and scientists. But if it’s really what you want to do, make sure you do all you can to work in this amazing field of expertise. If you’re not geographically restricted, consider looking for employment in other countries. The USA, for example, is always looking for good scientists to join police forces and usually ask for a science degree.

A body is found floating in a lake, the circumstances surrounding the death a complete mystery.

One might assume the cause of death to be drowning, and for this there may be certain pathological indicators. But failing these indicators, how can you be so sure that the victim drowned? It could be that they were killed elsewhere, their body tossed into the lake to eliminate suspicion. Or perhaps they did drown, but in alternative circumstances in another body of water. The scenarios are endless. But how can these questions be answered?

The key to this problem might just be a diverse group of microscopic algal organisms known as diatoms.

Perhaps you’ve heard of them. These asexually-reproducing organisms exist in a vast variety of shapes, sizes and colours, plentiful in many aquatic environments and existing in a tremendous range of populations. A particularly important feature of diatoms is their silica-based cell wall, producing an especially distinctive appearance that can vary greatly between different species. This cell wall enables diatoms to be particularly resistant to decay, so they may persist in an environment for a long time. It is their abundance, uniqueness and resistance that has allowed diatoms to be of such great use in the field of forensic limnology, that is the study of freshwater ecology in a legal context.

So how can these minute microorganisms help determine the circumstances surrounding a suspicious death?

Imagine a person drowning. As the head is submerged, water is inhaled into the lungs, along with any microorganisms contained in that water. In this case, diatoms. So the presence of diatoms in the lungs proves death by drowning? Not at all. Water can passively reach the lungs regardless of whether the victim was dead or alive by the time they reached the water. However if the victim is alive, when diatoms hosted by the water reach the lungs, they will be circulated around the body via the bloodstream, being deposited in different bodily tissues and internal organs.

So with this in mind, the investigator may be able to conclude that cause of death is likely to have been drowning if these diatoms are detected in the internal organs. At this point it is necessary to note that diatoms may already exist within the body, as these algal communities are found in various environments other than water. It is therefore necessary to establish a kind of match between the diatoms in the suspected drowning medium and those inside the body of the deceased. By studying the species of diatoms present and their abundance, it may be possible to conclude whether the diatom populations are consistent with one another. Interestingly diatom populations can also vary seasonally, thus may be able to provide some insight into the time of year in which a victim drowned based on the diatoms extracted from the remains. Comparisons such as these can be made by collecting water samples and extracting diatoms from bodily tissues and internal organs (often through acid extraction), before comparing the diatoms using light or electron microscopy.

The possible applications of the study of diatoms is by no means limited to these scenarios.

Numerous features of diatoms make these microorganisms an ideal focus for analysis in forensic investigations. Their minute size means that they can be readily transferred from the crime scene by objects or people, with perpetrators unlikely to be aware of the presence of these organisms. The resilience brought about by the silica-based cell wall allows for them to persist in the human body even beyond later stages of decomposition, during which time cause of death by pathological means may be more difficult. The distinctive morphology of diatoms allows for species to be distinguished from one another, and their abundance and variation results in different bodies of water developing very distinctive assemblages of diatoms.

Unfortunately the use of diatoms as an indicator of cause of death by drowning is somewhat controversial, highlighting the need for further research in this area of study.

References

Horton, B. P. Boreham, S. Hillier, C. The development and application of a diatom-based quantitative reconstruction technique in forensic science. 2006. University of Pennsylvania Scholarly Commons.

DNA fingerprinting, the process of producing a unique ‘fingerprint’ from a DNA sample, is something of a staple in forensic science. The ability to link a suspect to a crime scene or identify a set of remains has revolutionised legal investigations, being utilised in countless legal cases across the world since its discovery in 1984.

But once upon a time this renowned technique was just emerging, with its creator, geneticist Sir Alec Jeffreys of the University of Leicester, still unaware of just how beneficial his new technique would be to the criminal justice system. But how did this somewhat stumbled upon discovery end up becoming one of the most reliable forensic techniques available?

The story begins in late November 1983. 15-year-old Lynda Mann set off from her home in a small Leicestershire village to visit a friend, but unusually did not return. The following morning her raped and strangled body was found on a quiet footpath. Little evidence could be found other than a semen sample retrieved from her remains, though even this proved to be ineffective in leading investigators in the right direction.

But this would not be the last the world would hear of Lynda Mann. Just a few years after Lynda’s murder, another young girl went missing in July 1986. 15-year-old Dawn Ashworth had been walking home when she disappeared, her family’s worst fears soon confirmed when her brutally raped and strangled body was found two days later in the woods. Once again, a semen sample was found on the victim. The similarities between the two murders were not overlooked and, with a fresh influx of interest and evidence, the investigation could progress, with police believing the same man could be responsible for both crimes. Suspicion soon fell on Richard Burkland, a 17-year-old local who appeared to have suspicious knowledge of the latest incident. Under questioning he admitted to murdering one of the victims. Job done, the police might have thought.

Meanwhile at the University of Leicester Sir Alec Jeffreys and his team were working on a novel DNA fingerprinting technique. The technique had already been utilised in an immigration case involving a boy from Ghana, successfully proving that he was in fact the son of a family living in the UK. Recognising the potential power of this procedure and keen to apply it to a criminal case, investigators pulled Jeffreys’ and his new technique into the case.

Contrary to the belief of police, DNA profiling actually proved that Richard Burkland’s DNA did not match the semen found at the two crime scenes, pushing the investigation back to square one. Although this in itself was a ground-breaking scenario, the first ever exoneration of an innocent man using DNA fingerprinting, the murderer was still at large and the police had no more leads to follow.

With no other options, on 1st January 1987 Leicestershire Constabulary announced that they would be joining forces with the Forensic Science Service to conduct a huge DNA profiling project, collecting DNA samples from over 4000 local men in order to rule them out as suspects. However six months down the line a match had not been found. Were their efforts all for nothing?

Fortunately, a lucky break came from a particularly interesting conversation overheard in a local pub. Ian Kelly, an employee at a nearby bakery, was caught bragging about being paid £200 to submit a DNA sample on behalf of a work colleague. Living too far away from the area to have been required to give a sample himself, Kelly had apparently agreed to this request without many questions. Unsettled by the conversation, another employee soon raised the alarm, and Kelly was detained and questioned.

Kelly was covering for Colin Pitchfork, a local baker. Pitchfork had convinced Kelly that he would be framed for murder if his own blood sample was submitted, a story which was evidently enough to persuade Kelly to oblige.

On 19th September 1987, Pitchfork was arrested. After the new DNA profiling technique matched his DNA fingerprint to the crime scene samples, he admitted to raping and killing the two girls. Experts calculated the probability of this match occurring by chance to be 5.8 x 10-8. Pitchfork was sentenced to life imprisonment on 23rd January 1988.

Moral of this story – if you think you’ve gotten away with murder, you had better hope your mates don’t chat about it at the pub.